Resonant transition rates for charge transfer between diatomic molecular ions and simple metals

Abstract

We provide a parameter-free perturbation treatment of the resonant electronic coupling between a simple diatomic molecule (${\mathrm{H}}_{2}$) and a jelliumlike metal surface [Al(110)]. Assuming the unperturbed molecular and metallic states to be orthogonal (which is a good approximation), the matrix element simplifies to the form 〈${\ensuremath{\psi}}_{f}$\ensuremath{\Vert}H\ensuremath{\Vert}${\ensuremath{\psi}}_{i}$〉, where ${\ensuremath{\psi}}_{f}$ is the neutral free-molecule final state, ${\ensuremath{\psi}}_{i}$ the product of the unperturbed metallic and molecular-ion wave functions, and H the Coulomb interaction of the metal electron with the nuclei and 1\ensuremath{\sigma} electron in ${\mathrm{H}}_{2}$${\mathrm{}}^{+}$. Using scaled linear-combination-of-atomic-orbitals ${\mathrm{H}}_{2}$${\mathrm{}}^{+}$, scaled Heitler-London ${\mathrm{H}}_{2}$, and jellium wave functions, this matrix element, including its spin dependence, is evaluated. With use of the golden-rule expression, the transition rates for charge transfer to the ${\mathrm{H}}_{2}$ X ${\mathrm{}}^{1}$${\mathrm{\ensuremath{\Sigma}}}_{\mathrm{g}}^{+}$ and b ${}^{3}$${\ensuremath{\Sigma}}_{u}^{+}$ states are calculated. The dependence of these transition rates on molecule-axis orientation, distance from the surface, resonance energy, and internuclear separation, is investigated.